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Clinoenstatita en alpe arami peridotita: evidencia adicional de una presión muy alta
Bozhilov1, Green, Dobrzhinetskaya
1Institute of Geophysics and Planetary Physics and Department of Earth Sciences, University of California, Riverside, CA 92521, USA.
Science (New York, N.Y.)
|April 2, 1999
Resumen
La microscopía electrónica de transmisión reveló lámillas de clinoenstatita en el granate de los Alpes suizos lherzolita. Estos hallazgos sugieren la exhumación de rocas profundas de al menos 250 km antes de la colisión continental.
Área de la Ciencia:
- Mineralogía y Petrología.
- La geoquímica es la geoquímica.
- La tectónica es la tectónica.
Sus antecedentes:
- Las herzolitas de granate proporcionan información sobre la composición y las condiciones del manto superior de la Tierra.
- Comprender las lámelas de exsolución mineral ayuda a reconstruir las historias geológicas.
- El macizo de Alpe Arami es una localidad clave para el estudio de los xenolitos del manto.
Objetivo del estudio:
- Para investigar las microestructuras y la cristalografía de las láminas de clinoenstatita dentro de los granos de diopside.
- Para interpretar el proceso de exsolución e inferir las condiciones P-T de la roca huésped.
- Para determinar la profundidad de exhumación de la granada lherzolita de Alpe Arami.
Principales métodos:
- La microscopía electrónica de transmisión (TEM, por sus siglas en inglés) se utilizó para obtener imágenes de alta resolución de microestructuras minerales.
- Análisis cristalográfico de las láminas de exsolución.
- Análisis de las relaciones de fase dentro del sistema diopside-clinoenstatita.
Principales resultados:
- Lamellas de clinoenstatita fueron identificadas dentro de los granos de diopside de la lherzolita de granate de Alpe Arami.
- La orientación, la cristalografía y las microestructuras son consistentes con la exsolución de una fase de clinoenstatita centrada en C de alta presión.
- El análisis de las relaciones de fase apoya esta interpretación.
Conclusiones:
- La exsolución de clinoenstatita centrada en C indica la formación a altas presiones.
- La presencia de estas láminas implica que las rocas fueron exhumadas desde una profundidad mínima de 250 kilómetros.
- Este evento de exhumación probablemente ocurrió antes o durante la colisión continental.
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